MEXICO CITY — Parents of 43 missing students marked the six-month anniversary of their disappearance with a march of a few thousand supporters Thursday, urging fellow Mexicans not to abandon them but drawing far smaller numbers than rallies last year.

At the march's conclusion, Maria Elena Guerrero, the mother of a missing student, stood atop a stage and said her pain had turned to fury against Mexico's government in the months since her son disappeared.

"They have taken so much from us that they've even taken our fear," she said. "We're not afraid."

She pleaded with the crowd, "Don't leave us alone." The crowd responded by chanting that the families are not alone.

Earlier in the day parents and supporters demonstrated at the federal elections office in Mexico City to ask that voting scheduled for June in the southwestern state of Guerrero be suspended.

Dozens of protesters delivered a letter to the office asking that the June 7 elections not move forward because people could be voting for politicians tied to drug trafficking, as was the case with former mayor of Iguala, Jose Luis Abarca, who remains in custody.

Parents and their supporters later staged a protest march in the capital, while small bands of activists defaced campaign posters and burned a small bus in the Guerrero state capital of Chilpancingo.

The students from a rural teachers college were last seen in Iguala. Federal investigators say local police handed the students over to a drug gang, which killed them and incinerated their remains.

On Thursday, the Attorney General's Office issued a statement reiterating that the government had conducted a transparent and exhaustive investigation. It said 104 people had been detained in the case, including 48 from the Iguala police force.

Only one victim's remains have been identified, however, and parents of the young men have continued to demand answers about the events of Sept. 26.

"We came to tell authorities and the Mexican government that as parents we cannot allow the elections," said Meliton Ortega, parent of a student. "They have been six months of torture, of suffering for us."

Students from the Rural Normal School at Ayotzinapa went to Iguala on Sept. 26 to collect money and hijack buses, a common practice, so that they could attend events in Mexico City. But police confronted them in Iguala, firing on the buses. Six people were killed.

Federal investigators determined the police turned the students over to members of a drug gang who took them to a remote garbage dump near the town of Cocula, killed them, burned the bodies and threw the remains into a river.